CN209992560U - High-precision current sampling circuit - Google Patents
High-precision current sampling circuit Download PDFInfo
- Publication number
- CN209992560U CN209992560U CN201920423012.3U CN201920423012U CN209992560U CN 209992560 U CN209992560 U CN 209992560U CN 201920423012 U CN201920423012 U CN 201920423012U CN 209992560 U CN209992560 U CN 209992560U
- Authority
- CN
- China
- Prior art keywords
- resistor
- circuit
- operational amplifier
- voltage
- coupled
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Measurement Of Current Or Voltage (AREA)
Abstract
The utility model discloses a high accuracy current sampling circuit, including current sensor, bleeder circuit, difference amplifier circuit, current sensor coupling is between by the circuit and difference amplifier circuit, converts the electric current of by the circuit into voltage signal and exports to difference amplifier circuit; the voltage division circuit comprises a resistor R22 and a resistor R23 which are connected in series and have equal resistance values, and is used for dividing the power supply voltage and outputting the divided voltage to the differential amplification circuit; the differential amplification circuit comprises an operational amplifier, a resistor R25, a resistor R28, a resistor R26 and a resistor R27, wherein the resistor R25 is coupled between the voltage division circuit and the operational amplifier, the resistor R28 is coupled on the operational amplifier, the resistor R26 is coupled between the current sensor and the operational amplifier, the resistor R27 is coupled between the operational amplifier and the ground, the resistance values of the resistor R25 and the resistor R26 are equal to the resistance values of the resistor R27 and the resistor R28, and the resistance ratio of the resistor R25 to the resistor R28 is 1: 10. The utility model discloses simple structure, measurement accuracy is high.
Description
Technical Field
The embodiment of the utility model provides a current sampling circuit is related to particularly, relates to a high accuracy current sampling circuit.
Background
Current test products commonly used in the market are generally series resistance detection, and signals are easily interfered by a ground wire in the actual debugging process of the series resistance detection. In addition, when the current range is large, if the sampling resistance is small, signals are difficult to acquire when the current is small; when the sampling resistance is increased, the voltage of the operational amplifier is exceeded when the current is large, two-stage or even more than two-stage processing is needed under the conditions, the operation is very inconvenient, and the accuracy of the test is influenced.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to the above-mentioned defect among the prior art, provide a simple structure, measure convenient high accuracy current sampling circuit.
In order to realize the purpose of the utility model, the utility model adopts the following technical scheme: a high-precision current sampling circuit comprises a current sensor, a voltage division circuit and a differential amplification circuit, wherein the current sensor is coupled between a circuit to be tested and the differential amplification circuit and used for converting the current of the circuit to be tested into a voltage signal and outputting the voltage signal to the differential amplification circuit; the voltage division circuit comprises a resistor R22 and a resistor R23 which are mutually connected in series and have equal resistance values, and is used for dividing the power supply voltage and outputting the divided voltage to the differential amplification circuit; the differential amplification circuit comprises an operational amplifier, a resistor R25, a resistor R28, a resistor R26 and a resistor R27, wherein the resistor R25 is coupled between the voltage division circuit and the inverting input end of the operational amplifier, the resistor R28 is coupled between the inverting input end and the output end of the operational amplifier, the resistor R26 is coupled between the current sensor and the non-inverting input end of the operational amplifier, the resistor R27 is coupled between the non-inverting input end of the operational amplifier and the ground, the resistance values of the resistor R25 and the resistor R26 are equal to the resistance values of the resistor R27 and the resistor R28, and the resistance ratio of the resistor R25 to the resistor R28 is 1: 10.
Furthermore, the utility model discloses still provide following subsidiary technical scheme:
the current sampling circuit further includes a voltage follower coupled between the voltage divider circuit and the differential amplifier circuit.
The current sampling circuit further includes a potentiometer R24, the potentiometer R24 being coupled to the voltage follower for zeroing the voltage follower.
The current sampling circuit further comprises a first-order low-pass filter circuit coupled to the output of the operational amplifier, and comprising a resistor R51 and a capacitor C26.
The current sensor is an ACS712 type linear current sensor, the input power supply voltage of which is 5V, and the linear coefficient of which is 100 mV/A.
The differential amplifying circuit further comprises a potentiometer R29, the potentiometer R29 being coupled to the operational amplifier for zeroing the operational amplifier.
Compared with the prior art, the utility model has the advantages that: the current sampling circuit is simple in structure, the current sensor converts the measured current into a voltage signal, the differential amplification circuit processes the voltage signal to provide a common mode rejection ratio of the signal, the output signal is stable, and the measurement precision is high.
Drawings
In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the drawings that are needed in the description of the embodiments or related technologies will be briefly introduced below, and it is obvious that the drawings in the following description only relate to some embodiments of the present invention and are not limiting to the present invention.
Fig. 1 is a circuit diagram of a high-precision current sampling circuit of the present embodiment.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention more clearly understood, the following detailed description of the present invention, taken in conjunction with the accompanying drawings and the detailed description, is given in a non-limiting manner.
As shown in fig. 1, a high-precision current sampling circuit includes a current sensor, a voltage divider circuit, a voltage follower, a differential amplifier circuit, and a first-order low-pass filter circuit.
The current sensor is an ACS712 type linear current sensor, the ACS712 is completely designed based on the Hall sensing principle and comprises an accurate low-offset linear Hall sensor circuit and a copper foil which is positioned close to the surface of an IC, when current flows through the copper foil, a magnetic field is generated, a Hall element senses a linear voltage signal according to the magnetic field, the linear voltage signal is output through an internal amplifying circuit, a filtering circuit, a chopping circuit and a correcting circuit, the voltage signal is output from a pin 7 of a chip, and the current magnitude of the current flowing through the copper foil is directly reflected. The ACS712 has three ranges according to the difference of the suffix: the input and the output are in good linear relation in the range of measurement range, and the coefficients of Sensitivity are 185mV/A, 100mV/A and 66mV/A respectively. In this embodiment, the 1 st and 2 nd pins (IP + terminals) of the ACS712 are connected to the V1 terminal of the branch under test, and the 3 rd and 4 th pins (IP-terminals) are connected to the V2 terminal of the branch under test; the 5 th pin is grounded; pin 6 (filter) is connected to capacitor C24; the 7 th pin is an analog signal output end which is connected with the differential amplification circuit and outputs the converted voltage signal to the differential amplification circuit; the 8 th pin (power end of the device) is connected with a power end (VCC) with the voltage of 5V, and the pin is also connected with a capacitor C25 for filtering the clutter of the power supply. The current of the circuit to be tested flows into the ACS712 through the 1 st, 2 nd, 3 rd and 4 th pins, the current is converted into a voltage signal and then is output from the 7 th pin, and the relation between the output and the input is Vout-0.5 Vcc + Ip-sensing, and the chip of the embodiment adopts a chip with sensing of 100mV/a, and Vout-0.5 Vcc +0.1 Ip.
The voltage dividing circuit comprises a resistor R22 and a resistor R23 which are connected in series and have the same resistance, and the resistance of the two resistors is 100K. In this example, the voltage divider circuit is coupled to a power supply terminal (VCC) having a voltage of 5V, and since the resistance values of the resistor R22 and the resistor R23 are equal, the divided voltage is 2.5V.
The voltage follower U10 adopts OP-07 bipolar operational amplifier, the non-inverting input end of the operational amplifier is connected between the resistor R22 and the resistor R23, the inverting input end of the operational amplifier is connected with the output end to form negative feedback, the output end of the operational amplifier is connected with the differential amplifier circuit, and the 2.5V voltage divided by the voltage divider circuit is output to the differential amplifier circuit after voltage following. A potentiometer R24 is connected to the 7 th, 1 th and 8 th pins of the voltage follower, and the potentiometer R24 is used for zeroing the voltage follower U10.
The differential amplification circuit is used for amplifying a voltage signal and comprises an operational amplifier U11, a resistor R25, a resistor R28, a resistor R26, a resistor R27 and a potentiometer R29, wherein the operational amplifier adopts an OP-07 bipolar operational amplifier, the resistance of the resistor R25 is equal to the resistance of the resistor R26, the resistance of the resistor R27 is equal to the resistance of the resistor R28, and the resistance ratio of the resistor R25 to the resistor R28 is 1:10, the resistance ratio of the resistor R26 to the resistor R27 is 1: 10. one end of the resistor R25 is connected with the output end of the voltage follower, the other end of the resistor R25 is connected with the inverting input end of the operational amplifier, and the resistor R28 is coupled between the inverting input end and the output end of the operational amplifier to form a negative feedback circuit; one end of the resistor R26 is connected with the 7 th pin of the current sensor, the other end of the resistor R26 is connected with the non-inverting input end of the operational amplifier, one end of the resistor R27 is connected with the non-inverting end of the operational amplifier, and the other end of the resistor R27 is grounded; the potentiometer R29 is connected to the 7 th, 1 th and 8 th pins of the operational amplifier for zeroing the operational amplifier U11.
The first-order low-pass filter circuit is composed of R51 and C26, a resistor R51 is connected between the output end of an operational amplifier of the differential amplification circuit and the single chip microcomputer, a capacitor C26 is connected between the output end of the operational amplifier and the ground, and the first-order low-pass filter circuit is used for filtering high-frequency signals.
During testing, the terminals V1 and V2 are connected in series in a circuit, and the current is tested. U9 converts the measured current into voltage signal and outputs the voltage signal from pin 7, and the voltage signal output from pin 7 is VIoutThe signal is processed by a differential amplification circuit composed of U11, and the common mode rejection ratio of the signal is provided, so that the output of the signal is stabilized. U10 is a voltage follower, and since R22 and R23 have equal resistance values, the potential of the 3 rd pin of U10 is 2.5V, and the potential of the 6 th pin of U10 is also 2.5V. From the differential circuit composed of U11 and the peripheral components, the output voltage at pin 6 of U11 is:
wherein, R25 ═ R26 ═ 10K, R28 ═ R27 ═ 100K,
the above equation is simplified:
Vport＝10VIOUT-25
further simplifying as follows:
Vport＝10×(2.5+0.1Ip)-25
this gives:
Vport＝Ip
therefore, the singlechip directly samples the voltage value of the 6 th pin of the U11, and the voltage value is actually the sampled current value in terms of value.
It should be noted that the above-mentioned preferred embodiments are only for illustrating the technical concepts and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to implement the present invention accordingly, and the protection scope of the present invention cannot be limited thereby. All equivalent changes and modifications made according to the spirit of the present invention should be covered by the protection scope of the present invention.
Claims (6)
1. A high accuracy current sampling circuit which characterized in that: comprises a current sensor, a voltage division circuit and a differential amplification circuit, wherein,
the current sensor is coupled between the tested circuit and the differential amplifying circuit and is used for converting the current of the tested circuit into a voltage signal and outputting the voltage signal to the differential amplifying circuit;
the voltage division circuit comprises a resistor R22 and a resistor R23 which are mutually connected in series and have equal resistance values, and is used for dividing the power supply voltage and outputting the divided voltage to the differential amplification circuit;
the differential amplification circuit comprises an operational amplifier, a resistor R25, a resistor R28, a resistor R26 and a resistor R27, wherein the resistor R25 is coupled between the voltage division circuit and the inverting input end of the operational amplifier, the resistor R28 is coupled between the inverting input end and the output end of the operational amplifier, the resistor R26 is coupled between the current sensor and the non-inverting input end of the operational amplifier, the resistor R27 is coupled between the non-inverting input end of the operational amplifier and the ground, the resistance values of the resistor R25 and the resistor R26 are equal to the resistance values of the resistor R27 and the resistor R28, and the resistance ratio of the resistor R25 to the resistor R28 is 1: 10.
2. A high precision current sampling circuit according to claim 1, wherein: a voltage follower is also included, the voltage follower being coupled between the voltage divider circuit and the differential amplifier circuit.
3. A high accuracy current sampling circuit according to claim 2, wherein: and the potentiometer R24 is also included, and the potentiometer R24 is coupled with the voltage follower and used for carrying out zero setting on the voltage follower.
4. A high precision current sampling circuit according to claim 1, wherein: the circuit further comprises a first-order low-pass filter circuit, wherein the first-order low-pass filter circuit is coupled to the output end of the operational amplifier and comprises a resistor R51 and a capacitor C26.
5. A high precision current sampling circuit according to claim 1, wherein: the current sensor is an ACS712 type linear current sensor, the input power supply voltage of the current sensor is 5V, and the linear coefficient is 100 mV/A.
6. A high precision current sampling circuit according to claim 1, wherein: the differential amplifying circuit further comprises a potentiometer R29, the potentiometer R29 is coupled with the operational amplifier for zeroing the operational amplifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920423012.3U CN209992560U (en) | 2019-03-29 | 2019-03-29 | High-precision current sampling circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920423012.3U CN209992560U (en) | 2019-03-29 | 2019-03-29 | High-precision current sampling circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN209992560U true CN209992560U (en) | 2020-01-24 |
Family
ID=69290603
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201920423012.3U Expired - Fee Related CN209992560U (en) | 2019-03-29 | 2019-03-29 | High-precision current sampling circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN209992560U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113428096A (en) * | 2021-08-27 | 2021-09-24 | 武汉元丰汽车电控系统股份有限公司 | Data acquisition card, apparatus and method |
| CN115097197A (en) * | 2022-07-06 | 2022-09-23 | 中国华能集团清洁能源技术研究院有限公司 | Auxiliary circuit of current sensor and current sensor |
-
2019
- 2019-03-29 CN CN201920423012.3U patent/CN209992560U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113428096A (en) * | 2021-08-27 | 2021-09-24 | 武汉元丰汽车电控系统股份有限公司 | Data acquisition card, apparatus and method |
| CN115097197A (en) * | 2022-07-06 | 2022-09-23 | 中国华能集团清洁能源技术研究院有限公司 | Auxiliary circuit of current sensor and current sensor |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN106679841B (en) | A kind of temperature-detecting device and temperature checking method | |
| CN209992560U (en) | High-precision current sampling circuit | |
| CN103703380B (en) | Measure differential voltage | |
| CN106443159B (en) | Current detection chip | |
| CN221376891U (en) | Low-cost high-precision temperature acquisition automatic calibration circuit | |
| CN115097275A (en) | Device and method for reducing the temperature influence in measuring switching currents | |
| CN211206616U (en) | Hall current sensor with temperature compensation | |
| CN220650862U (en) | Current calibration circuit for current sense amplifier | |
| JPS6325572A (en) | Leakage current measuring system of electrometer amplifier | |
| CN218767097U (en) | Current detection device and electrical equipment | |
| CN111208346B (en) | Small signal voltage measuring device and method | |
| CN113155159B (en) | Bridge detector | |
| CN204228286U (en) | A kind of Moisture Meter temperature collection circuit | |
| CN206378535U (en) | A kind of detection platform of small resistor resistance | |
| CN211576401U (en) | Low-impedance temperature sensor | |
| TR202020541A1 (en) | A TEMPERATURE SENSING SYSTEM WITH THE THERMISTOR | |
| CN113820029A (en) | PT100 temperature acquisition circuit for acquisition terminal | |
| CN2816770Y (en) | Temperature and temperature difference measuring device | |
| CN116972998A (en) | Temperature measurement circuit, temperature acquisition device and processing equipment | |
| CN217278623U (en) | Line load network detection and fault positioning device | |
| CN113341213B (en) | Portable friction nano generator sensor powered by single power supply | |
| CN219935963U (en) | Voltage and current measurement channel of digital bridge and digital bridge | |
| CN217738500U (en) | Conditioning circuit of piezoresistive pressure sensor | |
| CN219084253U (en) | High-precision temperature sampling circuit | |
| CN219574243U (en) | High-resistance fault loop resistance precision measurement circuit for railway signal cable |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20200124 Termination date: 20210329 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |